Are abnormal yolk sac characteristics important factors in abortion rates?

BACKGROUND
This study was undertaken to determine if there were different abortion rates between normal and abnormal yolk sacs.


MATERIALS AND METHODS
In this cohort study, the yolk sac characteristics of 193 consecutive pregnant women, of 5-6.5 weeks gestation, with normal body mass index (BMI) were prospectively evaluated. All patients underwent two-dimensional transvaginal ultrasonography, which was performed by the same sonographer. We considered the following yolk sac characteristics as normal for classification: diameter: 2-5 mm; round shape; absence of degenerative changes; equal number with embryos; echogenic rim and hypoechoic center. Yolk sacs that had diameters smaller than 2 mm or larger than 5 mm; a shape that was not round (i.e., oval or distorted); the presence of degenerative changes; hyper- or hypo-echogenic rim; hyperechoic center and unequal number with embryos were considered abnormal. Based on the above classification, patients were divided into two groups, study (abnormal yolk sac) and control (normal yolk sac). The study group contained 22 cases and the control group consisted of 164 cases. The primary outcome measure was the abortion rate between both groups. Chi-square and students't test were used for data analysis.


RESULTS
A total of 193 cases were evaluated. We excluded 2 cases. Among the remaining 191 cases, 22 (11.51%) had abnormal yolk sacs of which spontaneous abortion occurred in 14 (63.63%) cases. In the control group, out of 169 (89.49%) cases, spontaneous abortion was noted in 6 (3.55%). There was a statistically significant difference in abortion rates between the two groups (p=0.000).


CONCLUSION
According to the results of this study, it is obvious that abnormal yolk sac characteristics are associated with spontaneous abortion.


Introduction
tional sac is the yolk sac, which should be detectable as a regularly rounded extra-amniotic structure when the gestational sac reaches dimensions of 8 in cases with no yolk sac, a yolk sac with dimen-of the yolk sac and the yolk sac number, which should be the same as the number of embryos as In a normal pregnancy it should be possible to --falls outside the 5 th th -equal or larger than 5 mm on early ultrasound are also associated with a threefold increased risk for factors such as age, body mass index, polycystic The lack of a yolk sac or a smaller than gesta---This study was undertaken to determine if there were different abortion rates between normal and abnormal yolk sacs.

Materials and Methods
-formed consent was obtained from all patients. This The following patients were excluded: those patients with diabetes, hypertension, or any systemic disease, those who expressed unwillingness --raphy was performed by the same sonographer.
es, equal number with embryos, the presence of an that had diameters smaller than 2 mm or larger than echogenic rim, hyperechoic center, and unequal number with embryos were considered abnormal.  O yolk sac was present and a spontaneous abortion yolk sac was present and a spontaneous abortion ocof pregnancy which was stopped by the use of progesterone preparations. With the exception of one abortion continued to term. In one case of this group, the pregnancy was terminated at 34 weeks because of oligohydramnios, but the fetus was normal and had no problems cases. Pregnancy continued to term in the remaining -With regards to yolk sac characteristics of the conall of which had a round shape.

Discussion
tional sac, which must be present when the mean pregnancy outcome to assess the yolk sac measure-nal ultrasonography and repeat the assessment one to two weeks later when a discrepancy is detected and its relation to the spontaneous abortion rate.
sound are associated with a threefold increased risk of tant factor for prediction of spontaneous abortion.
nancy were a good indication that the probability mal pregnancy and the presence of a yolk sac with of certain diseases and the pregnancy loss in these of larger yolk sac diameters amongst type 1 diabetic Abnormal yolk sac shape are associated with ab-cation of abnormal yolk sacs may suggest the death yolk sacs had normal pregnancies.
Failure to detect the presence of a yolk sac before case that had no yolk sac in the eighth week of pregnancy. This case aborted the fetus after one week. and the number of sacs must equal the number of twin pregnancy the yolk sacs are always separated by a septum. They are not separated in a monochorisacs, whose pregnancy had a normal outcome. and hypoechoic center. In the current study there -that this particular characteristic of the yolk sac was not an important factor for an abortion.

Conclusion
acteristics are associated with spontaneous abor-Thus, it is presumed that among the yolk sac charthe most important factors for early pregnancy loss.
additional studies with larger numbers of cases.